Energy Changes C5 Flashcards
What happens to energy in an exothermic reaction?
The energy of the reactants is increasedIt is transferred to the surroundings
causing a temperature increase
What happens to energy in an endothermic reaction?
it is taken in from the surroundings causing a fall in temperature
Give an example of an exothermic reaction
Combustion reactions, neutralisation reactions, many oxidation reactions.
What is activation energy?
The minimum amount of energy needed to start a reaction. Energy is required to break the bonds in the reactants
What are reaction profiles?
Diagrams that show the relative energies of the reactants and products of the reaction
What is an electrochemical cell?
A basic system made up of two different electrodes in contact with an electrolyte that produces energy
What is a fuel cell?
A fuel cell is an electrical cell thats supplied with a fuel and oxygen and uses energy from that reaction to produce electrical energy efficiently
What is a important thing to remember when measuring energy transfer?
To keep the reaction container insulated to reduce energy loss to the surroundings. Another thing to remember is to keep a lid on the reaction container to prevent evaporation.
Is energy released when bonds are formed? What about when they are broken?
When bonds are formed, energy is released in to the surroundings
When bonds are broken, energy is required from the surroundings
What is an electrode?
What is an electrolyte?
An electrode is a conducting element, while electrolytes are an ionic solution that conducts electricity that reacts with the electrodes
How is a difference in charge created?
The electrodes are made of different metals so they react differently with the same electrolyte which causes a charge difference
What type of reaction does a hydrogen-Oxygen reaction involve?
It is a redox reaction.
In a Hydrogen-Oxygen fuel cell, O2 and H2 react to form H2O, How does this reaction produce a current between the electrodes?
On the anode side, Hydrogen forms positive ions, the electrons are attracted to the anode
On the cathode side, Oxygen forms negative ions, accepting electrons from the cathode
The Hydrogen ions and Oxygen ions react to form water and a current flows between the electrodes.
Why should batteries not be put in house hold waste
Alkali/Metal waste could be corrosive/toxic or could ignite
Recycling could also save resources
What factors affect the voltage produced by a cell
Type of electrodes
Type of electrolyte
Temperature of electrolyte
Concentration of electrolyte
Surface area of electrodes
Distance between electrodes
Connecting multiple cells in series produces a higher voltage in battery
